Preparation of alpha, omega-substituted-bis-n-alkylthiopropane-1, 3 compounds



United States Patent 3,361,808 PREPARATION OF a,w-SUESTITUTED-P-iS-n- ALKYLTHIOPROPANE-L3 CGMPGUNIBS Derek L. Ransley, Berkeley, Calif assignor to Chevron Research Company, a corporation of Delaware No Drawing. File-d Nov. 15, 1963, Ser. No. 323,928 4 Claims. (Ci. 260-533) The present invention is directed to a process for the production of t -functionally-substituted 1,3-propanedithiol derivatives.

More particularly, it is directed to the production of (1,0: difunctionally substituted bis-n-alkylthiopropane-1,3 compounds characterized by the general formula:

in which Z is a functional group relatively inert to free radical chemical attack and R represents branchedand straight-chain alkylene radical groups having from 1 to 5 carbon atoms per group.

In the process of the present invention, an iii-substituted alkyl thiol is contacted under autogenous pressure conditions with allene, preferably in the presence of an organic inert liquid diluent under liquid phase free radical reaction conditions. Under these conditions, the subject u,w-functionally substituted bis-alkylthiopropane-1,3 compounds are produced in high yields.

By inert liquid diluents is meant those relatively unreactive organic solvents such as alkanes, aromatic hydrocarbons, benzene, chlorobenzene, bromobenzene, cyclohexane, heptane, octane and the like which do not compete favorably underv free radical reaction conditions with thiols and allene in a determinative product sense to produce or yield free radicals. That is, no solvent molecule becomes a component of the compounded products under reaction conditions.

By liquid phase free radical reaction conditions is meant the contacting of a liquid mixture of thiol and allene, preferably allene and thiol in the presence of an inert liquid diluent under catalytic free radical generating conditions, including thermal dissociation of known organic free radical precursor compounds, such as organic peroxidic and organic azo compounds, as well as free radical generation in the reaction medium by irradiation by radiant energy, including high energy, high frequency vibrational means, light, electron bombardment and the like.

In general, suitable reaction temperatures are in the range from below about 150 C. to just above the temperature of the melting point for the particular reaction mixture. Preferably, reaction temperatures below about 100 C. are employed.

Representative free radical precursor compounds are azobis-isobutyronitrile, benzoyl peroxide, di-tertiary butyl peroxide, cumene hydroperoxide, methyl ethyl ketone hydroperoxide, lauroyl diperoxide, t-butylperacetate, t-butylperbenzoate, di-t-butyldiperthalate and the like, that is, known organic compounds capable of thermal dissociation at temperatures below 150 0, thereby yielding free radical fragments capable of initiating free radical nhexyl thiol addition to n-hexene-l. In general, from about Patented Jan. 2, 1968 1-10 mol percent (based on thiol) of the free radical precursor compounds is required.

In a preferred embodiment of the present process, benzene and the desired iii-substituted thiol, for example, HS(CH OH, are charged to an autoclave in which the relative volume relationship of benzene to thiol employed is about 05-100 volumes of benzene for each volume of the thiol. In addition, allene in an amount such that the mol ratio of thiol to allene is preferably about 2:1, which corresponds to stoichiometric requirements, and from about 1-4% (based on thiol) of a free radical reaction catalyst, for example, azobis-isobutyronitrile, are charged to the autoclave. Under autogenous pressure and at a temperature of about 50 C., reaction commences as shown by a drop in the autoclave pressure. When the autoclave pressure becomes relatively stabilized, an increase of temperature, for example, to C. and higher, usually serves to drive the reaction farther towards completion. In general, reaction periods of from 0.5l0 hours are adequate but may vary depending upon the particular feed, its purity and the particular free radical initiator means employed. In any event, the reaction is best and most conveniently monitored by following the pressure change. In general, and because the products are stable compounds, recoveries by distillation or distillation under reduced pressure are most convenient.

Representative substituent groups corresponding to Z of the general formula include HO, HO C,

and the like.

These functional groups have in common the property that they are relatively inert to free radical attack in the presence of the sulfhydryl group (SH) and allene functionalities. All known substituent groups are satisfactory which are essentially unaffected under the following free radical relative reactivity test conditions:

Temperature, C. 50 Allene, 'rnols 0.1 n-I-Iexyl thiol 0.2 n-HeXyl-X 0.2 Azobis-isobutyronitrile, grams 1-4 Time, hours 0.2 Pressure Autogenous TABLE I.CONDITIONS AND PRODUCT DISTRIBUTION FROM THE REACTION OF ALLENE WITH MERCAPTANS RS131 RSH, mols Allene, AIBN, Time, min. Yield, 1 Product mols Percent Percent r 0. 250 0.125 1. 3 97. 0 g HOCHQCHP t 2.100 0. 900 2.0 40 a4. 0 i HOOH2OH2S 1 CHzOHtCHfl HooCorr-r- 0. 214 0. 2.9 255 97. 7 (HOzCCH2S)2(-CH2CH1CH HOOCCHQCHP 0. 200 0.100 3.1 245 97. 0 (H02CCHQCHZS )Z(CHQCHZCHQ) 1 Yield based on thiol reacted.

[P- 3 2 e 4 2 a l 2 z z z) and the like.

The foregoing descriptive embodiments of the present invention are illustrative only. It is not the intent that the invention shall be construed as limited to the details TABLE Ill-PRODUCT CHARACTERIZATIONS Calculated Found RSCH2CH2CH2S R Calculated Found N M.P. or

M01. Wt. M01. Wt. B.P., C. C, Percent H, Percent C, Percent H, Percent HOCHzCHg 42. 82 8. 21 43. 00 8. 17 196 1. 5485 2 159-161 HOOCCHz- 224 1 225 CH O O G CH2 42. 83 6. 39 42. 68 6. 16 252 1. 5094 141-143 HO O CCHZCHP 42. 85 6. 39 42. 74 6. 49 252 1 254 105. 5-107 1 From neutralization equivalent.

TABLE III.NMR AND IR 013 SULFIDES MADE FROM ALLENE RSCH2CHzCHz-SR NMR Expressed as ppm. Pertinent IR,

HOCH2OHz- 4.91(T) r 3.9l(Q 2.86(T). 2.04(P) 3,500 HOOOOHCH 10.62(S) 2.6-2.9(M) 1.906) 1,710 HOOCCH2 1089(8) 3.54(S) 2.90(T) 2.04(P) 1, 710 CH OOOCH 3.70(S) 3.29(S) 2.73(1) 1.86(I) 1, 755, 1, 280

* NMR run in CD01 b Downfield from tetramethylsilane.

= Ill-defined pentuplet.

Methylene adjacent to 0 0 and those next to sulfur overlap.

(S) Singlet, (D) Doublet, (T) Triplet, (Q) =Quartet, (P) Pentuplet, (M) =Multiplet.

From the foregoing it is seen that excellent yields of oc,w-difllI1CtiOnal bis-n-a1kylthiopropane-l,3 products are obtained in the present process. Particularly is this the case when the ratio of thiol to allene is at least 1.8 to 1. Excess thiol over 2.0 to 1 does not interfere with the reaction. The optimum and preferred ratio is about 2.0 to 1. The range 1.8 to 2.2 to l of thiol to allene, respectively, is desirably employed.

In direct contrast to the single product obtained by use of the unsubstituted thiol adducts of the present invention, such adducts as methyl thiol, ethyl thiol, phenyl thiol and p-Cl phenyl thiol were found to yield complex product mixtures containing from 2-5 different products, each being present in substantial amounts.

The bifunctional products of the present invention are useful per se as antioxidants by reason of their sulfur atom content. They are appreciably soluble in general in both polar and nonpolar solutions. By reason of their bifunctionality, they are particularly useful as additives and monomers for the production of resins and polymeric products.

Representative ii-substituted thiols useful in the present process are: HO(CH SH, HO CCH SH,

CH OSO (CH 8H, NC (CH 5H, CH O (CI-I 8H, Br (CH 8H, Cl (CH 8H, p-CH O CCcI-I (CH 5H,

rn-HO CC H (CI-I 3H, HO (CH 5H, HO CCH CHCH CH SH and the like. Lower alkyl carboxylate esters are preferred, that is, methyl, ethyl and propyl esters.

Representative products resulting from the reaction of the above thiols in the present process with allene are:

of the description, except insofar as such limitations have been included in the terms of the following claims.

What is claimed is: 1. Process for the production of a,w-difunctionallysubstituted bis-alkylthiopropane-1,3 compounds characterized by the general formula:

wherein R is an alkylene radical having from 1 to 5 carbon atoms per group, and Z is a functional substituent group relatively inert to free radical chemical attack which comprises reacting in the liquid phase a thiol characterized by the general formula:

and allene, said reaction being initiated by free radicals generated by thermal dissociation of free radical precursor compounds selected from the group consisting of 7 and recovering the resulting reaction product mixture containing the corresponding a,w-difunctionally-substi tuted bis-alkylthiopropane-1,3 compound in high yield.

2. Process for the production of a,w-hydroxy-bis-nalkylthiopropane-l,3 compounds which comprises reacting allene and an w-hydroxy-n-alkylthiol in the liquid phase in the presence of an inert organic liquid diluent, said reaction being initiated by free radicals generated by thermal dissociation of organic free radical precursor compounds, at a temperature below about C. and a pressure suflicient to maintain said liquid phase, wherein said thiol contains from 1 to 5 carbon atoms per molecule, wherein the relative volume ratio of said thiol and said liquid diluent is in the range 1 to 0.5 to 100, respectively, and wherein the mole ratio of said thiol to allene is in the range 1.8 to 2.2 to 1, respectively, and recovering the resulting reaction product mixture containing the corresponding m,w-hydroxy-bis-n-alkyl-thiopropane-1,3.

3. Process for the production of a,w-carboXy-bis-nalkylthiopropane-1,3 compounds which comprises reacting allene and an w-carboxy-n-alkylthiol in the liquid phase in the presence of an inert organic liquid diluent, said reaction being initiated by free radicals generated by a source selected from the group consisting of thermal dissociation of organic peroxidic compounds, or organic azo compounds; radiant energy irradiation, high energy high frequency vibration and electron bombardment at a temperature below about 100 C. and at a pressure sufficient to maintain said liquid phase and wherein said thiol contains from 1 to 5 carbon atoms per molecule and recovering the resulting reaction product mixture containing the corresponding a,w-carboxy-bis-nalkylthiopropane-1,3.

4. Process of claim 3 wherein said free radical generating condition is thermal dissociation of organic free radical precurson compounds, wherein the relative volume ratio of said thiol and said liquid diluent is in the range 1 to 0.5 to 100, respectively, and wherein the mol ratio of thiol to allene is in the range 1.8 to 2.2 to 1, respectively.

References Cited UNITED STATES PATENTS 6/1959 Koening et al. 260481 XR OTHER REFERENCES LORRAINE A. WELNBERGER, Primary Examiner. S. B. WILLIAMS, Assistant Examiner. 

1. PROCESS FOR THE PRODUCTION OF A,W-DIFUNCTIONALLYSUBSTITUTED BIS-ALKYLTHIOPROPANE-1,3 COMPOUNDS CHARACTERIZED BY THE GENERAL FORMULA: 